I think you have lichen planus. This is a fairly common, nonserious, nonsexual condition of no known cause. When it affects the penis, it's pretty easy to control using mild but prescription-strength cortisone creams. Let a dermatologist take a look and meantime, check out the scrotum bumps, which are almost certainly normal. You don;t have to avoid sex or any other activity if you have this condition--just treat it from time to time when it becomes visible.
Best.
Dr. Rockoff